1. Field of the Disclosure
This disclosure relates generally to integrating an electrical power source with a light source in an apparatus, and switching the light source on and off based on a magnetic field. Some embodiments of the disclosure relate to switching a lighted insert on and off in a magnetostrictive device such as a hand-held ultrasonic magnetostrictive dental device.
2. Background Description
Magnetostrictive ultrasonic dental hand-pieces are used in dentistry to remove calculus from teeth and perform other cleaning or abrasive operations by vibrating a metal insert at an ultrasonic frequency. A magnetostrictive ultrasonic dental hand-piece typically receives electric current having a controlled frequency from a generator and translates the received electrical energy into a mechanical motion of a tip of an insert coupled to the dental hand-piece. To this end, a magnetostrictive dental hand-piece includes an electrical connector, a coil, and a housing functioning as a handle. Alternating current provided to the coil induces a corresponding alternating magnetic field. At a resonant frequency, a stack of metal plates disposed within the coil may vibrate in response to the alternating magnetic field, and these vibrations may be transferred to the tip.
Since a mouth is a small and dimly-lit space in which to work, it is desirable to have an ultrasonic dental tool that can bring light directly into and around the working area, e.g., tooth and gumline surfaces. It is further desirable to omit an additional power cord for the light to minimize the number of obstructions that may get in the way of a dental practitioner's task at hand. Several known approaches exist where light is delivered to the tip end of a magnetostrictive insert by using available power in the coil of the hand-piece without needing an additional power cord.
In one known approach, a magnetostrictive ultrasonic dental insert includes a first coil or transducer for generating ultrasonic vibrations and producing the mechanical motion of the dental tip. A second coil or transducer generates a voltage signal in response to the mechanical movement. A light source in the vicinity of the tip receives the voltage signal from the second transducer and illuminates. This approach has several disadvantages. First, the intensity of the generated light may vary based on power fluctuations delivered to the first coil, such as when an operator varies tip vibration rate by varying the power to the hand-piece. Second, the intensity of the light may vary based on the integrity of the stack itself. Furthermore, this approach does not allow the light source to be turned on when the tip is not vibrating, as the voltage generated by the second transducer and used to illuminate the light source necessarily requires energizing the first transducer and stack.
In another known approach, a magnetostrictive ultrasonic dental device includes a similar primary coil for generating ultrasonic vibrations and the mechanical motion of the dental tip. A secondary coil is positioned to be inductively coupled to the primary coil and electrically connected to the light source. The secondary coil is oriented so that a magnetic field induced by energizing the first coil induces, in turn, a current flow in the second coil that causes the light source to illuminate. Like the first discussed approach, this other approach also suffers from varying intensities of the light source based on power fluctuations delivered to the first coil. Similarly, in this approach, the light source may not be turned on independent from tip vibration.